AP Psych Barrons

Researcher Ernest Hilgard explained hypnosis in a different way in his dissociation theory.
According to Hilgard, hypnosis causes us to divide our consciousness voluntarily. One part or level of
our consciousness responds to the suggestions of the hypnotist, while another part or level retains
awareness of reality. In an experiment investigating hypnotism and pain control, Hilgard asked
hypnotized participants to put their arm in an ice water bath. Most of us would feel this intense cold as
painful after a few seconds, but the hypnotized participants reported no pain. However, when Hilgard
asked them to lift their index finger if any part of them felt the pain, most participants lifted their
finger. This experiment demonstrated the presence of a hidden observer, a part or level of our
consciousness that monitors what is happening while another level obeys the hypnotist’s suggestions.
DRUGS
Psychoactive drugs are chemicals that change the chemistry of the brain (and the rest of the body) and
induce an altered state of consciousness. Some of the behavioral and cognitive changes caused by
these drugs are due to physiological processes, but some are due to expectations about the drug.
Research shows that people will often exhibit some of the expected effects of the drug if they think
they ingested it, even if they did not (this is similar to the placebo effect).
All psychoactive drugs change our consciousness through similar physiological processes in the
brain. Normally, the brain is protected from harmful chemicals in the bloodstream by thicker walls
surrounding the brain’s blood vessels. This is called the blood-brain barrier. However, the molecules
that make up psychoactive drugs are small enough to pass through the blood-brain barrier. These
molecules either mimic or block naturally occurring neurotransmitters in the brain. The drugs that
mimic neurotransmitters are called agonists. These drugs fit in the receptor sites on a neuron that
normally receive the neurotransmitter and function as that neurotransmitter normally would. The
drugs that block neurotransmitters are called antagonists. These molecules also fit into receptor sites
on a neuron. However, instead of acting like the neurotransmitter, they simply prevent the natural
neurotransmitters from using that receptor site. Other drugs prevent natural neurotransmitters from
being reabsorbed back into a neuron, creating an abundance of that neurotransmitter in the synapse.
No matter what mechanism they use, drugs gradually alter the natural levels of neurotransmitters in
the brain. The brain will produce less of a specific neurotransmitter if it is being artificially supplied
by a psychoactive drug.
This change causes tolerance, a physiological change that produces a need for more of the same
drug in order to achieve the same effect. Tolerance will eventually cause withdrawal symptoms in
users. Withdrawal symptoms vary from drug to drug. They range from the headache I might get if I do
not consume any caffeine during the day to the dehydrating and potentially fatal night sweats
(sweating profusely during sleep) a heroin addict experiences during withdrawal. Dependence on
psychoactive drugs can be either psychological or physical or can be both. Persons psychologically
dependent on a drug feel an intense desire for the drug because they are convinced they need it in
order to perform or feel a certain way. Persons physically dependent on a substance have a tolerance
for the drug, experience withdrawal symptoms without it, and need the drug to avoid the withdrawal
symptoms. Different researchers categorize psychoactive drugs in different ways, but four common
categories are stimulants, depressants, hallucinogens, and opiates.